Battery module and its method of manufacture

ABSTRACT

A rechargeable battery that prevents a concentration of stress on a coupling portion of a lead tab and a cap assembly at a time of bending the lead tab so as to not damage the coupling portion includes: an electrode assembly having a first electrode, a second electrode, and a separator interposed between the first and second electrodes; a case to receive the electrode assembly and having an open top portion; a cap assembly arranged on the top portion of the case; a lead tab having one end affixed to the cap assembly to electrically connect the cap assembly to the first electrode; and a stopper fixed to the cap assembly and having one end arranged on the lead tab, the stopper allowing a portion of the lead tab contacting the one end of the stopper to be bent when the lead tab is bent.

CLAIM OF PRIORITY AND CROSS-REFERENCE TO RELATED APPLICATIONS

This application makes reference to, incorporates the same herein, andclaims all benefits accruing under 35 U.S.C. §119 and §120 from anapplication earlier filed in the Korean Intellectual Property Office on19 Jan. 2007 and there duly assigned Serial No. 10-2007-0006173.Furthermore, this application is a divisional and a continuationapplication of Applicants' Ser. No. 12/010,083 filed in the U.S. Patent& Trademark Office on 18 Jan. 2008, and assigned to the assignee of thepresent invention.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a rechargeable battery and its methodof manufacture, and more particularly, the present invention relates toa rechargeable battery having an enhanced lead tab coupling structureand its method of manufacture.

2. Description of the Related Art

Rechargeable batteries can repeatedly charge and discharge due to areversible transformation between chemical energy and electrical energythereof. Nickel-cadmium batteries, Nickel-hydrogen batteries, andlithium rechargeable batteries are widely used rechargeable batteries.The lithium rechargeable battery has an operating voltage of 3.6V ormore. The operating voltage of the lithium-cadmium battery is threetimes higher than that of the nickel-cadmium battery or thenickel-hydrogen battery. In addition, the lithium rechargeable batteryhas a high energy density per unit weight. Therefore, recently, thelithium rechargeable battery has been widely used as a power source forportable electronic apparatuses. The lithium rechargeable battery isclassified as a lithium-ion rechargeable battery, a lithium-ion polymerbattery, and a lithium polymer battery.

A typical rechargeable battery includes an electrode assembly having ananode, a cathode, and a separator disposed between the anode and thecathode, a case containing the electrode assembly, and a cap assemblycoupled to the case to seal the case. The anode and the cathode areprovided with respective uncoated anode and cathode parts that are notcoated with an activation material. The uncoated anode and cathode partsare disposed in different directions.

The uncoated cathode part is coupled to a cathode collector plateelectrically connected to the case, and the uncoated anode part iscoupled to an anode collector plate electrically connected to the capassembly.

The cap assembly and the anode collector plate are connected to eachother by a lead tab made of a conductive metal. The lead tab is weldedto the cap assembly and the anode collector plate. The lead tab in abent state is disposed between the cap assembly and the anode collectorplate.

However, conventionally, when the lead tab is subject to a bendingprocess, stress is concentrated on a coupling portion of the lead taband the cap assembly. Therefore, the coupling portion may be damaged.Accordingly, the damage may cause degradation in performance of therechargeable battery. Moreover, if the coupling portion is broken, theanode and the cap assembly are electrically disconnected, so that therechargeable battery cannot function.

SUMMARY OF THE INVENTION

The present invention has been made in an effort to provide arechargeable battery having advantages of preventing concentration ofstress on a coupling portion of a lead tab and a cap assembly at a timeof bending the lead tab so as not to damage the coupling portion.

An exemplary embodiment of the present invention provides a rechargeablebattery including: an electrode assembly having a first electrode, asecond electrode, and a separator interposed between the first andsecond electrodes; a case to contain the electrode assembly andincluding an open top portion; a cap assembly disposed on the topportion of the case; a lead tab including one end affixed to the capassembly to electrically connect the cap assembly to the firstelectrode; and a stopper affixed to the cap assembly and having one endarranged on the lead tab, the stopper facilitating a portion of the leadtab contacting the one end of the stopper to be bent when the lead tabis bent.

The one end of the stopper may be disposed on a portion of the lead tabseparated from the portion of the lead tab affixed to the cap assembly.The one end of the stopper may be disposed on the portion of the leadtab affixed to the cap assembly.

The cap assembly may include a cap plate, and one end of the lead tabmay be affixed to an edge of one surface of the cap plate.

The stopper may be fixed to the cap assembly by welding. In addition,the stopper may be welded and fixed to a portion of the cap assembly towhich the lead tab is welded.

Another embodiment of the present invention provides a rechargeablebattery including: an electrode assembly having a first electrode, asecond electrode, and a separator interposed between the first andsecond electrodes; a case to receive the electrode assembly andincluding an open top portion; a cap assembly disposed on the topportion of the case and including a cap plate; and a lead tab connectingthe cap plate to the first electrode, wherein a portion of the lead tabseparated from one end thereof is affixed to an edge of one surface ofthe cap plate by, and wherein an end of a first portion of the lead tab,disposed on one side of the portion of the lead tab affixed to the capplate, is bent toward a second portion of the lead tab disposed on anopposite side thereof.

The end of the first portion of the lead tab may be disposed on theportion of the lead tab affixed to the cap plate. In addition, the endof the first portion of the lead tab may be disposed on a portion of thesecond portion separated from the portion of the lead tab affixed to thecap plate.

The rechargeable battery may further include a first electrode collectorplate disposed on an upper portion of the first electrode to beelectrically connected to the first electrode, wherein the lead tab iscoupled to a lead member connected to the first electrode collectorplate.

Yet another embodiment of the present invention provides a method ofmanufacturing a rechargeable battery including: forming a firstelectrode, a cap plate, and a lead tab to electrically connect the firstelectrode to the cap plate; affixing a portion of the lead tab separatedfrom one end thereof to an edge of one surface of the cap plate; bendingan end of a first portion of the lead tab, disposed on one side of theportion of the lead tab affixed to the cap plate, toward a secondportion of the lead tab, disposed on an opposite side thereof; andbending a portion of the second portion contacting the first portionwhen bending the second portion.

In bending the first portion of the lead tab, the end of the firstportion may be disposed on the portion of the lead tab affixed to thecap plate.

In bending the first portion of the lead tab, the end of the firstportion may be disposed on a portion of the second portion separatedfrom the portion of the lead tab affixed to the cap plate.

The lead tab may be affixed to the cap plate by welding.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the present invention, and many of theattendant advantages thereof, will be readily apparent as the presentinvention becomes better understood by reference to the followingdetailed description when considered in conjunction with theaccompanying drawings in which like reference symbols indicate the sameor similar components, wherein:

FIG. 1 is an exploded perspective view of a rechargeable batteryaccording to a first embodiment of the present invention.

FIG. 2 is a partially enlarged cross-sectional view of FIG. 1.

FIG. 3 is a cross-sectional view of a rechargeable battery according toa second embodiment of the present invention.

FIG. 4 is a cross-sectional view of a rechargeable battery according toa third embodiment of the present invention.

FIG. 5 is a flowchart for explaining a rechargeable batterymanufacturing method according to an embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, exemplary embodiments of the present invention aredescribed in detail with reference to the accompanying drawings in orderfor a person ordinarily skilled in the art to easily implement thepresent invention. The present invention may be modified in variousdifferent ways, and is not limited to the described embodiments. Forclarity, description of some constructions and elements not directlyrelated to the present invention have been omitted. Like referencenumerals denote like elements. Detailed descriptions of well-knownfeatures have been omitted.

FIG. 1 is an exploded perspective view of a rechargeable battery 100according a first embodiment of the present invention. In the firstembodiment, a lithium ion rechargeable battery is used as an example ofthe rechargeable battery 100 for explaining the principles of thepresent invention. However, the present invention is not limited to thelithium ion rechargeable battery.

As shown in FIG. 1, the rechargeable battery 100 includes an electrodeassembly 110, a case 120, and a cap assembly 140.

The electrode assembly 110 includes a first electrode (anode) 114 formedby applying an anode activation material to a collector plate, a secondelectrode (cathode) 112 formed by applying a cathode activation materialto a collector plate, and a separator 113 disposed between the anode 114and the cathode 112 to prevent a short-circuit therebetween.

More specifically, the cathode 112 is constructed by coating aslurry-type activation material layer in which a cathode activationmaterial powder, a cathode binder, and a binding material are mixed on acollector plate, such as a copper plate. The cathode activation materialpowder may be formed by using, as a main material, a carbon materialsuch as natural graphite, artificial graphite, a graphite-type carbon, anon-graphite-type carbon, or a combination thereof.

An uncoated cathode part 112 a that is not coated with the activationmaterial layer is formed along a lower edge of the cathode 112. Theuncoated cathode part 112 a contacts and is connected to a cathodecollector plate 132 disposed at the bottom of the case. Accordingly, thecathode 112 is electrically connected to the case 120, so that the case120 can function as a cathode terminal of the rechargeable battery.

On the other hand, the anode 114 is constructed by coating a slurry-typeactivation material layer in which an anode activation material powder,an anode binder, and an anode conductive additive are mixed on acollector plate, such as an aluminum plate. The anode activationmaterial powder may be formed by using a lithium metal oxide such asLiCoO₂, LiMnO₂, LiNiO₂, LiCrO₂, and LiMn₂O₄.

An uncoated anode part 114 a that is not coated with the activationmaterial layer is formed along an edge of the anode 114. The uncoatedanode part 114 a is connected to an anode collector plate 138 that isdisposed above the uncoated anode part 114 a. The anode collector plate138 is connected to the cap assembly 140 through a lead member 138 a anda lead tab 150.

The separator 113 has functions of separating the cathode 112 from theanode 114 and providing a transport channel for lithium ions. Theseparator may be constructed of a single-layered film of polyethylene,polypropylene, or polyvinylidene fluoride, or a multi-layered filmformed of two or more layers thereof. In addition, the separator may beconstructed as a complex multi-layered film, such as a two-layeredseparator of polyethylene/polypropylene, a three-layered separator ofpolyethylene/polypropylene/polyethylene, and a three-layered separatorof polypropylene/polyethylene/polypropylene.

The electrode assembly 110 is formed by sequentially stacking thecathode 112, the separator 113, and the anode 114, providing a centralbar to one end of the stacked structure, and trimming the stackedstructure into a substantially cylindrical shape. The electrode assembly110 is inserted into the case 120, and the central bar is drawn out fromthe electrode assembly 110. A center pin (not shown) is inserted into ahollow portion formed by drawing out the central bar.

The central pin prevents deformation of the electrode assembly 10 duringa charge or discharge period of the rechargeable battery 100. Thecentral pin has a shape of a hollow cylinder. The central pin may bemade of iron, copper, nickel, a nickel alloy, or other metals. Inaddition, the central pin may be made of a polymer.

Alternatively, without drawing out the aforementioned central bar fromthe electrode assembly 110, the central bar may be used as a substitutefor the central pin. Such a modification is well-known to a person ofordinary skill in the art.

The case 120 has a substantially cylindrical space that contains theelectrode assembly 110. The case 120 is made of a conductive metallicmaterial such aluminum, an aluminum alloy, and nickel-coated steel. Thetop portion of the case 120 is initially open, so that the electrodeassembly 110 can be inserted into the case 120 through the open topportion.

The cap assembly 140 is coupled to the open top portion of the case 120to seal the case 120. During a process of coupling the case 120 to thecap assembly 140, a bead portion 123 and a crimp portion 125 are formedin the case 120.

In addition, an electrolyte solution (not shown) is injected into thecase 120. Lithium ions generated by an electrochemical reaction betweenthe cathode 112 and anode 114 during the charging and dischargingperiods can be transported due to the electrolyte solution.

The cap assembly 140 includes a positive temperature coefficient element141, a safety vent 142, an electrode cap 143, a gasket 144, an insulator145, a cap plate 146, and a sub-plate 147.

The gasket 144 is disposed between the case 120 and the electrode cap143, the positive temperature coefficient element 141, and the safetyvent 142 to surround circumferences of the electrode cap 143, thepositive temperature coefficient element 141, and the safety vent 142.Therefore, the gasket 144 isolates the electrode cap 143, the positivetemperature coefficient element 141, and the safety vent 142 from thecase 120.

The safety vent 142 has a hollow protrusion portion 142 a at the centralportion thereof. The safety vent 142 is electrically connected to theanode 114 through the cap plate 146, the sub-plate 147, the lead tab150, and the anode collector plate 138, which are disposed under thesafety vent 142. For the electrical connection to the anode 114, theprotrusion portion 142 a is fixed to the sub-plate 147 by welding, andthe lead tab 150 is fixed to the cap plate 146 and the lead member 138 aof the anode collector plate 138 by welding.

When an internal pressure of the rechargeable battery 100 increases to apredetermined pressure or more due to some problem, the safety vent 142is designed to be electrically disconnected from the anode 114. Morespecifically, when the internal pressure of the rechargeable battery 100increases excessively, the protrusion portion 142 a of the safety vent142 and the welding portion of the sub-plate 147 are disconnected due tothe increasing internal pressure. Therefore, the safety vent 142 can beelectrically disconnected from the anode 114 by the insulator 145disposed under the safety vent 142. Moreover, when the internal pressureof the rechargeable battery 100 further increases, the safety vent 142is ruptured. A gas in the rechargeable battery 100 can be vent throughthe ruptured portion of the safety vent 142 and a venting hole 143 a.

The positive temperature coefficient element 141 is connected to anupper portion of the safety vent 142. Electrical resistance of thepositive temperature coefficient element 141 increases to almostinfinity when the temperature of the element 141 is over a predeterminetemperature. Therefore, when the temperature of the rechargeable battery100 is more than a predetermined temperature, a flow of the charging anddischarging current can be stopped by using the positive temperaturecoefficient element 141. However, when the temperature of therechargeable battery 100 drops down to the predetermined temperature,the electrical resistance of the positive temperature coefficientelement 141 decreases, so that the functions of the rechargeable battery100 can be recovered.

The rechargeable battery 100 according to the first embodiment includesseparate safety elements for preventing over-charge, over-discharge,over-heat, and over-current as well as the aforementioned safety vent142 and positive temperature coefficient element 141.

The venting hole 143 a is provided to a side of the electrode cap 143.The electrode cap 143 is connected to an upper portion of the positivetemperature coefficient element 141 to function as an anode terminal forapplying current outwards.

The insulator 145 is disposed between the safety vent 142 and the capplate 146. A hole is formed to penetrate central portions of theinsulator 145 and the cap plate 146, and the protrusion portion 142 a ofthe safety vent 142 penetrates the hole to contact with the sub-plate147. Except for the protrusion portion 142 a of the safety vent 142, theother portions thereof are electrically isolated from the cap plate 146.In such a construction, when a welding portion of the protrusion portion142 a of the safety vent 142 and the sub-plate 147 is disconnected, thesafety vent 142 can be electrically disconnected from the anode 114.

One side of the lead tab 150 is fixed on the cap plate 146, and theother side thereof is fixed to the lead member 138 a of the anodecollector plate 138, so that the cap plate 146 can be electricallyconnected to the anode 114. The lead tab 150 may be fixed to the capplate 146 and the lead member 138 a by welding.

The lead member 138 a may be integrally formed with the anode collectorplate 138. Alternatively, the lead member 138 a may be fixed to theanode collector plate 138 by welding a separately-formed member to theanode collector plate 138.

FIG. 2 is a cross-sectional view of the lead tab 150 coupled to the capassembly 140. The coupling structure of the lead tab 150 is described indetail below with reference to FIG. 2.

A portion of the lead tab 150 spaced apart from one end thereof is fixedto an edge of one surface of the cap plate 146 by welding. An end of afirst portion 151 of the lead tab 150, arranged on one side of thewelding portion 160, is bent toward a second portion 152 of the lead tab150 arranged on the opposite side thereof. Due to the bending, the endof the first portion 151 is arranged on the second portion 152.

The other end of the second portion 152 of the lead tab 150 opposite tothe end connected to the welding portion is connected to the lead member138 a of the anode collector plate 138 disposed under the cap plate 146.The lead member 138 a is integrally formed with the anode collectorplate 138. However, the present invention is not limited thereto.

The second portion 152 of the lead tab 150 is bent to be coupled withthe lead member 138 a (see FIG. 1). When the second portion 152 is bent,a portion of the second portion 152 contacting the end of the firstportion 151 is bent. Conventionally, when the second portion 152 of thelead tab 150 is bent, the welding portion 160 is bent, so that thewelding portion 160 may be damaged. However, according to the firstembodiment, when the second portion 152 is bent, the portion 152 a thatis separated by a predetermined distance from the welding portion 160 isbent. Accordingly, concentration of stress on the welding portion 160 isprevented.

FIG. 3 is a cross-sectional view of a portion of a rechargeable batteryaccording to a second embodiment of the present invention. As shown inFIG. 3, an end of a first portion 251 of a lead tab 250 is arranged onthe welding portion 160. Other technical features except for theaforementioned construction are the same as those of the firstembodiment.

According to the second embodiment, when a second portion 252 of thelead tab 250 is bent, a portion 252 a of the second portion 252separated by a predetermined distance from the welding portion 160 isbent to contact an end of the first portion 251 of the lead tab 250.Accordingly, when the second portion 252 is bent, concentration ofstress on the welding portion 160 is prevented.

FIG. 4 is a cross-sectional view of a rechargeable battery according toa third embodiment of the present invention. Referring to FIG. 4, an endof a lead tab 350 is fixed on an edge of one surface of the cap plate146 by welding. The welding may be laser welding or resistance welding.The other end of the lead tab 350 is coupled to the lead member 138 a(see FIG. 1) of the anode collector plate 138 (see FIG. 1).

A stopper 351 is fixed to the cap plate 146 by welding. The stopper 351is bent toward the lead tab 350 so that an end of the stopper 361 isdisposed on a portion of the lead tab 350 separated by a predetermineddistance from the welding portion 360. Alternatively, the one end of thestopper 351 may be disposed on the welding portion 360. In addition, thestopper 351 may be connected to the welding portion, that is, thecoupling portion of the cap plate 146 and the lead tab 350 as well asthe cap plate 146.

The lead tab 350 is bent to be coupled with the lead member 138 a. Whenthe lead tab 350 is bent, the lead tab 350 is bent at the portion 352 acontacting the one end of the stopper 351.

Conventionally, when the lead tab 350 is bent, the welding portion 360is bent, so that the welding portion 360 may be damaged. According tothe third embodiment, when the lead tab 350 is bent, the portion 352 athat is separated by a predetermined distance from the welding portion360 is bent, so that concentration of stress on the welding portion 360is prevented.

FIG. 5 is a flowchart for explaining a rechargeable batterymanufacturing method according to an embodiment of the present invention

Referring to FIG. 5, firstly, a first electrode, a cap plate, and a leadtab for electrically connecting the first electrode and the cap plateare formed (not shown).

Next, a portion of the lead tab separated by a predetermined distancefrom one end thereof is welded to an edge of one surface of the capplate (S10).

Next, an end of a first portion of the lead tab, arranged on one side ofthe welding portion, is bent toward a second portion of the lead tabarranged on the opposite side (S20).

Subsequently, the one end of the first portion is arranged on a portionof the second portion separated by a predetermined distance from thewelding portion (S30). Alternatively, the one end of the first portionmay be arranged on the welding portion of the lead tab and the capplate.

Next, the second portion of the lead tab is bent (S40). The portion ofthe second portion separated by a predetermined distance from thewelding portion is bent to contact the end of the first portion.Accordingly, concentration of stress on the welding portion 160 isprevented.

Finally, the second portion of the lead tab is coupled to the leadmember of the anode collector plate by welding (S50).

According to the rechargeable battery manufacturing method, when thelead tab is bent, the coupling portion of the lead tab is not bent, butrather a portion that is separated from the coupling portion is bent. Asa result, damage to the coupling portion is prevented.

Although the present invention can be implemented with variousembodiments, the embodiments are exemplified for description of theprinciple of the present invention. However, the present invention isnot limited thereto. Therefore, the present invention is not limited tothe aforementioned embodiments, and it will be understood by a person ofordinarily skill in the art that various modifications and changes maybe made without departing from the spirit and scope of the presentinvention.

As described above, according to the embodiments of the presentinvention, due to a stopper or a first portion of a lead tab, when thelead tab is bent, concentration of stress on a coupling portion of thelead cap and a cap assembly is prevented.

In addition, since stress is not concentrated on the coupling portion, aprocess of bending the lead tab can be easily performed, so that amanufacturing process time can be reduced.

While this invention has been described in connection with what ispresently considered to be practical embodiments, it is to be understoodthat the present invention is not limited to the disclosed embodiments,but, on the contrary, is intended to cover various modifications andequivalent arrangements included within the spirit and scope of theappended claims.

What is claimed is:
 1. A rechargeable battery comprising: an electrodeassembly having a first electrode, a second electrode, and a separatorinterposed between the first and second electrodes; a case to receivethe electrode assembly, the case including an open top portion; a capassembly arranged on the open top portion of the case; a lead tab havingone end affixed to the cap assembly to electrically connect the capassembly to the first electrode; and a stopper affixed to the capassembly and having one end arranged on the lead tab, the stopperfacilitating a portion of the lead tab contacting the one end of thestopper when the lead tab is bent.
 2. The rechargeable battery of claim1, wherein the one end of the stopper is arranged on a portion of thelead tab separated from the portion of the lead tab affixed to the capassembly.
 3. The rechargeable battery of claim 1, wherein the one end ofthe stopper is arranged on the portion of the lead tab affixed to thecap assembly.
 4. The rechargeable battery of claim 1, wherein the capassembly includes a cap plate, one end of the lead tab being affixed toan edge of one surface of the cap plate.
 5. The rechargeable battery ofclaim 1, wherein the stopper is welded to the cap assembly.
 6. Therechargeable battery of claim 5, wherein the stopper is welded to aportion of the cap assembly affixed to the lead tab.
 7. The rechargeablebattery of claim 1, wherein the one end of the lead tab is welded to thecap assembly.
 8. A rechargeable battery comprising: an electrodeassembly having a first electrode, a second electrode, and a separatorinterposed between the first and second electrodes; a case to receivethe electrode assembly, the case including an open top portion; a capassembly arranged on the top portion of the case and including a capplate; a lead tab connecting the cap plate to the first electrode; aportion of the lead tab separated from one end thereof affixed to anedge of one surface of the cap plate; and an end of a first portion ofthe lead tab, arranged on one side of the portion of the lead tab thatis affixed to the cap plate, and bent toward a second portion of thelead tab arranged on an opposite side of the portion of the lead tabaffixed to the cap plate.
 9. The rechargeable battery of claim 8,wherein the end of the first portion of the lead tab is disposed on theportion of the lead tab affixed to the cap plate.
 10. The rechargeablebattery of claim 8, wherein the end of the first portion of the lead tabis arranged on a portion of the second portion separated from theportion of the lead tab affixed to the cap plate.
 11. The rechargeablebattery of claim 8, further comprising: a first electrode collectorplate arranged on an upper portion of the first electrode andelectrically connected to the first electrode; and the lead tab coupledto a lead member connected to the first electrode collector plate. 12.The rechargeable battery of claim 8, wherein the portion of the lead tabaffixed to the cap plate is welded thereto.
 13. A rechargeable batterycomprising: a first electrode, a cap plate, and a lead tab electricallyconnecting the first electrode to the cap plate; a portion of the leadtab separated from one end thereof affixed to an edge of one surface ofthe cap plate; an end of a first portion of the lead tab, arranged onone side of the portion of the lead tab affixed to the cap plate, andbent toward a second portion of the lead tab arranged on an oppositeside thereof; and a portion of the second portion contacting the firstportion.
 14. The rechargeable battery of claim 13, wherein an end of thefirst portion is arranged on the portion of the lead tab affixed to thecap plate.
 15. The rechargeable battery of claim 13, wherein an end ofthe first portion is disposed on a portion of the second portionseparated from the portion of the lead tab affixed to the cap plate. 16.The rechargeable battery of claim 13, wherein the portion of the leadtab is welded to the cap plate.
 17. The rechargeable battery of claim 8,wherein the second portion of the lead tab arranged on an opposite sideof the portion of the lead tab affixed to the cap plate comprises astopper affixed to the cap assembly and having one end arranged on thelead tab, the stopper facilitating a portion of the lead tab contactingthe one end of the stopper when the lead tab is bent.